From: SeongJae Park <sj@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: SeongJae Park <sj@kernel.org>, Jakub Acs <acsjakub@amazon.de>,
damon@lists.linux.dev, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: [PATCH v2 4/5] mm/damon/lru_sort: avoid divide-by-zero in hot threshold calculation
Date: Fri, 20 Oct 2023 17:23:16 +0000 [thread overview]
Message-ID: <20231020172317.64192-5-sj@kernel.org> (raw)
In-Reply-To: <20231020172317.64192-1-sj@kernel.org>
When calculating the hotness threshold for lru_prio scheme of
DAMON_LRU_SORT, the module divides some values by the maximum
nr_accesses. However, due to the type of the related variables, simple
division-based calculation of the divisor can return zero. As a result,
divide-by-zero is possible. Fix it by using damon_max_nr_accesses(),
which handles the case.
Reported-by: Jakub Acs <acsjakub@amazon.de>
Fixes: 40e983cca927 ("mm/damon: introduce DAMON-based LRU-lists Sorting")
Cc: <stable@vger.kernel.org> # 6.0.x
Signed-off-by: SeongJae Park <sj@kernel.org>
---
mm/damon/lru_sort.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
index 3ecdcc029443..f2e5f9431892 100644
--- a/mm/damon/lru_sort.c
+++ b/mm/damon/lru_sort.c
@@ -195,9 +195,7 @@ static int damon_lru_sort_apply_parameters(void)
if (err)
return err;
- /* aggr_interval / sample_interval is the maximum nr_accesses */
- hot_thres = damon_lru_sort_mon_attrs.aggr_interval /
- damon_lru_sort_mon_attrs.sample_interval *
+ hot_thres = damon_max_nr_accesses(&damon_lru_sort_mon_attrs) *
hot_thres_access_freq / 1000;
scheme = damon_lru_sort_new_hot_scheme(hot_thres);
if (!scheme)
--
2.34.1
next prev parent reply other threads:[~2023-10-20 17:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-20 17:23 [PATCH v2 0/5] avoid divide-by-zero due to max_nr_accesses overflow SeongJae Park
2023-10-20 17:23 ` [PATCH v2 1/5] mm/damon: implement a function for max nr_accesses safe calculation SeongJae Park
2023-10-20 17:23 ` [PATCH v2 2/5] mm/damon/core: avoid divide-by-zero during monitoring results update SeongJae Park
2023-10-20 17:23 ` [PATCH v2 3/5] mm/damon/ops-common: avoid divide-by-zero during region hotness calculation SeongJae Park
2023-10-20 17:23 ` SeongJae Park [this message]
2023-10-20 17:23 ` [PATCH 5/5] mm/damon/core: avoid divide-by-zero from pseudo-moving window length calculation SeongJae Park
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